How it's done
Structural insulated panels (SIPs) are panels with a core of rigid foam insulation between an exterior and interior skin. The most common materials used for the skins are structural Oriented Strand Board (OSB) or plywood. The foam cores are composed of expanded polystyrene, extruded polystyrene, or polyurethanes. The two skins in combination with the integral insulation core carry all of loads of the structure. The foam insulation keeps the two skins aligned, acting as a web, and provides the insulation value. There are some panels systems that have ribs, which are structural members that carry some or most of the load. While these are not true with SIPs, they are often discussed in the same category of wall system.
Insulation is one of the key components of an energy-efficient home. With heating and cooling accounting for 50% of energy use in the average home, the type of insulation you choose can save thousands of dollars in utility bills over the life of the building.
Insulation is rated by R-value (which measures a material’s thermal resistance). An insulating material with a higher R-value forms a more effective thermal barrier between the outside temperature and the space inside the home.
But an R-value doesn’t tell the whole story. Lab tests that determine R-value have little resemblance to how insulation actually performs in a home. When real-world factors such as air infiltration, extreme temperatures, and thermal bridging are present, field-installed fiberglass insulation can lose more than half of it’s R-value. Research has shown that SIPs provide continuous insulation that will maintain its stated R-value for the life of the home and outperform fiberglass insulation every time.
The panels have good insulation value since the various types of foam insulation used to fill the wall cavity provide uniform insulation coverage and has a relatively higher effective insulation value. SIP systems are quite energy efficient since there is very little thermal bridging and there is a good opportunity to produce a low air leakage structure. Both of these factors contribute to the energy efficiency of SIP wall systems. The panels are quite light-weight (depending on panel size) and the smaller sizes can be carried and placed using manual labour. This allows for installation where heavy equipment is not available or accessible, and can easily be done by framers or someone with carpentry skills. Installation is quick, which is helpful with tight schedules or during inclement weather. The walls are straight and smooth for the interior finishes and exterior cladding. The application of these finishes is easy since it is possible to nail anywhere on the wall surface.
The sequencing of construction should not be significantly altered with this type of wall system, although some of the tasks will change. In many instances, conventional floor and roof systems can be used, with the conventional exterior walls simply converted to structural insulated panels. This will not require changing the order in which trades are involved. Insulation of exterior walls obviously is eliminated, while dealing with the installation of wiring may require an extra step. As with other components, such as trusses and windows, the structural insulated panels must be ordered well in advance so they can be delivered on time to the site in order to fit into the framing schedule. Other accessories, such as lintels and splines, also need to be accounted for.
The primary service that will be affected is electrical. Some manufacturers provide channels (vertically and/or horizontally) to allow for the installation of the wires. If this is not done, other options must be considered, such as altering the way that the wiring is done, or even strapping the inside to accommodate the insulated panels. Modifying or adding openings in the walls is possible but must be done with full knowledge of the limitations to altering the structural skins. As with any wall system, care must be taken to distribute loads over openings.
At NW Building Systems our team of skilled tradesmen have constructed numerous custom-built homes & commercial projects for First Nations communities. ISC & CMHC submission services are also offered.
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